Making Organic Poultry Feed More Sustainable: Dehulling Homegrown Protein Crops

1. Making organic poultry feed more sustainable:
Dehulling homegrown protein crops
Authors:
Dr Cliff Nixey, Poultry Xperience
Tony Little, Organic Centre Wales
Date: April 2013
Page i

2. Acknowledgements
The authors wish to thank:
David Sanderson of Avlan Blanch and Howard Roberts of Hammond End farm who
hosted the study tour
Graham Perkins of PMR Ltd for his input on machinery sharing mechanisms.
The Better Organic Business Links (BOBL) project, run by Organic Centre Wales, is a four
year project designed to support the primary producer in Wales and grow the market for
Welsh organic produce in a sustainable way.
The aim is to develop markets for organic produce whilst driving innovation and promoting
sustainable behaviours at all levels within the supply chain, to increase consumer demand
and thence markets for organic produce, especially in the home market, and to ensure that
the primary producers are aware of market demands. The project provides valuable
market information to primary producers and the organic sector in general.
Delivery of the project is divided into five main areas of work:
1. Fostering innovation and improving supply chain linkages
2. Consumer information and image development of organic food and farming in
Wales
3. Market development
4. Providing market intelligence to improve the industry's level of understanding of
market trends and means of influencing consumer behaviour
5. Addressing key structural problems within the sector.
In all elements of the work, the team are focused on building capacity within the organic
sector, to ensure that the project leaves a legacy of processors and primary producers with
improved business and environmental skills, able to respond to changing market
conditions, consumer demands and climate change.
The project is funded under the Rural Development Plan for Wales 2007-2013, in turn
funded by the Welsh Government and the European Agricultural Fund for Rural
Development
Page ii

3. Contents
Contents ............................................................................................................................. 3
Executive Summary ........................................................................................................... 1
1
Introduction ............................................................................................................... 2
2
Objectives .................................................................................................................. 2
3
Project activities ........................................................................................................ 2
4
The nutritional case for dehulling ............................................................................ 2
5
The dehulling process .............................................................................................. 3
6
Quantifying the benefits of dehulling ...................................................................... 4
6.1
Nutritional analysis ............................................................................................ 4
6.2
Least cost formulations ..................................................................................... 5
6.2.1 The principles ................................................................................................... 5
6.2.2 Calculating opportunity prices for dehulled peas and beans ............................. 6
6.2.3 Putting a value on dehulling .............................................................................. 6
7
Access to machinery ................................................................................................ 8
8
Conclusions ............................................................................................................... 9
Page iii

4. Executive Summary
Organic poultry rations are heavily dependent on imported soya to meet the protein
requirements of the birds. However, organic and GM-free soya is becoming increasingly
difficult, and therefore expensive, to source and relying so heavily on imports is not in
keeping with the organic ethos. One approach to the problem is to improve the nutritive
value of homegrown protein crops such as peas and beans, thus allowing them to replace
soya to a greater extent than is the case now. One way in which that can be achieved is by
removing the seed hulls.
The project looked at the potential contribution that dehulling can make by:
Examining the nutritional basis for dehulling
Quantifying the benefits associated with the process
Exploring how Welsh producers might access dehulling facilities at economic
prices.
Analysis of the nutritional composition of entire grani, dehulled seed and the hulls alone
were carried out for peas and beans. They confirmed that there is a nutritional benefit to
dehulling through increasing the relative proportions of crude protein, key amino acids and
starch and decreasing fibre content. Although anti-nutritional factors were not analysed as
part of the project, we can assume that their concentrations in the dehulled seed are low
because published data show clearly that these compounds are concentrated in the hulls.
The economic value added by dehulling was assessed by entering the nutritional data
obtained from the analyses into a ‘least cost’ ration formulator. This is a computer
programme which shows how the user can arrive at a given nutritional target using the
cheapest ingredients possible. A value was placed on the dehulled grain by calculating its
‘opportunity price’, that is the price at which it becomes competitive with alternative
ingredients. The opportunity price was calculated in the context of four poultry diets:
Turkey starter; turkey grower; broiler finisher; and chicken layer. The largest benefits were
seen for broiler and turkey diets, especially the latter which require higher protein levels.
If income could be derived from the separated hulls, the economic benefit of dehulling
would be enhanced and peas and beans could potentially be used at higher inclusion rates
and in more diets. Possible uses could include ruminant feeding and poultry/ pet litter.
The relatively high cost of purchasing a dehuller and the associated seed cleaning
equipment (£14,000 combined) may act as a disincentive for individual farmers to buy the
necessary equipment. Options for cost sharing and joint ownership are discussed.
Page 1 of 13

5. 1 Introduction
Organic poultry rations are heavily dependent on imported soya to meet the protein
requirements of the birds. However, organic and GM-free soya is becoming increasingly
difficult, and therefore expensive, to source and relying so heavily on imports is not in
keeping with the organic ethos. For a detailed examination of the issues, watch this short
film: http://streaming.aber.ac.uk/restricted/departments/ibers/Feed_from_the_Farm.wmv.
One approach to the problem is improve the nutritive value of homegrown protein crops
such as peas and beans, thus allowing them to replace soya to greater extent than is the
case now. One way in which that can be achieved is by removing the seed hulls.
2 Objectives
To examine the nutritional basis for dehulling
To quantify the benefits associated with the process
To explore how Welsh arable and poultry producers might access dehulling facilities
at economic prices
3 Project activities
These objectives were achieved through the following:
A leaflet (Appendix I), based on a literature review and expert opinion, outlining the
potential benefits of dehulling protein crops.
A study tour to see dehulling machines in action at:
o Alvan Blanch (Malmsbury Wilts), a manufacturer, for detailed information on
the dehulling process and technical specifications of the machine.
o Hammonds End Farm (Harpenden, Herts) to show how a dehuller can be
integrated into the farm’s grain handling system.
A video was made of the study tour and made available on the OCW website and
YouTube
Samples of peas and beans (entire and dehulled) were collected during the study
tour and analysed for nutritional content. This information was used to determine
the opportunity price for dehulled peas and beans using a least cost formulation
programme.
The Welsh Machinery Rings were consulted on arrangements that might facilitate
access to dehulling machines at economic cost
4 The nutritional case for dehulling
The use of peas is low and field beans rare in organic poultry diets. While they are
comparatively rich in protein, they are both low in methionine and cystine (Table 1). One of
the reasons for the lower nutrient content of peas and beans is the presence of a fibrous
outside hull. The hull also contains anti-nutritive factors such as tannins which reduce
digestibility of amino acids (see Box 1). For this reason a limit on inclusion is placed by
poultry nutritionists.
Page 2 of 13

6. The rationale is that if the outside hull was removed, the nutritive value of the remaining
seed, and its monetary value would be markedly increased, while the reduction in antinutritive factors would allow poultry nutritionists to include more in their diets at the
expense of soya.
Ingredient
Soya 44
Sunflower
Rapemeal
Peas
Beans
Fishmeal
Protein (%)
44
33
33.9
20.5
25
66
Lysine (%)
2.71
1.16
1.83
1.45
1.58
4.46
Methionine (%)
0.59
0.74
0.68
0.19
0.18
1.75
Meth + Cystine (%)
1.24
1.29
1.49
0.48
0.49
2.32
ME MJ/kg
11
7
7
11.4
11.85
12.85
Table 1: The protein and ME content of some key ingredients
Box1: Anti-nutritional factors in grain legumes
Tannins bind strongly with proteins and other large molecules such as starch, cellulose or
minerals. Tannins reduce intake by making the feed less palatable and form indigestible
compounds in the gut.
Trypsin inhibitors reduce the activity of trypsin, an enzyme involved in protein digestion. This, in
turn, reduces growth rate and feed efficiency in poultry. They occur mostly in legumes but are also
found in low concentrations in cereals.
Alkaloids: There are many types of alkaloids, which are specific to a particular plant species. The
one present in lupins, for instance, is quinolizidine. If ingested, they can have a wide range of
adverse effects and sometimes cause stock to refuse feed.
Plant lectins are found mostly in legume seeds or beans and have a specific affinity for sugar
molecules. As well as causing red blood cells to clump together (a process known as
agglutination), lectins may bind to cells in the gut lining. This reduces the action of some digestive
enzymes which, in turn, decreases the absorption of nutrients and ultimately slows growth.
5 The dehulling process
The process of dehulling is an entirely physical one. The machine (Figure 1) consists of a
series of rotating tubes which fling the seed against a metal ring. The initial impact cracks
the hull, which is scrubbed off the seed as it goes round the ring at high velocity. Once the
hulls have been removed, the grain is passed through a seed cleaning system which
separates the output into three fractions: the dehulled seed; the hulls; and any grains that
are left entire. This last can be fed back into the machine. For further information watch
this short film: (http://www.youtube.com/watch?v=3_dJAjuIvsM).
Two variables are important to ensure an efficient process:
The speed of the dehuller, that is the velocity with which the grain is flung against
the metal ring: Too slow and the hull will not crack; too fast and the seed shatters.
Manufacturers issue guidelines for each crop, but a period of trial and error is
usually required to fine tune it once it is installed.
The rate at which grain is fed in to the machine: If you go too fast, the system
becomes flooded. This slows the dehuller down which makes it less efficient.
Page 3 of 13

7. With peas and beans you can realistically expect a throughput of 1.5 tonnes/ hour. The
combined cost of the machine and the seed cleaning equipment is approximately £14,000
new.
Figure 1: Impact dehuller (Credit Alvan Blanch)
6 Quantifying the benefits of dehulling
The benefits of dehulling were assessed by analysing the nutrient content of the dehulled
seed, the separated hulls and the entire grain for each of peas and beans. This information
was used to determine the contribution the processed grain could make to a ‘least cost’
poultry ration (section 6.2).
6.1
Nutritional analysis
The results of the analyses are shown in Table 2. Due to the high cost of amino acid
analysis, only lysine and methionine were analysed directly. The cystine, threonine,
tryptophane and arginine values were calculated by using published figures which
establish the relative proportions of the different amino acids in peas and beans. Similarly,
the ME has been calculated using the equation based on protein, oil, sugar and starch,
Page 4 of 13

8. originally developed for wheat. This will introduce a small error into the data, but it is
unlikely to have a significant impact on the conclusions.
Another potential source of error could arise because only a small amount of material is
used in the analysis which may not be representative of the whole batch of material. This
could, for example, explain the very high starch figure (66%) for dehulled peas which
implies that about two thirds of the pea was hull; this is clearly not the case. When entering
in the nutrient values in the least cost formulation system, a judgement based on
experience and other published data has had to be used to arrive at logical comparisons.
Peas
Nutrient %
Crude protein
Crude fibre
Moisture
Oil (B )
Lysine
Methionine
Sugar
Starch
M.E. MJ/kg (calculated)
Meth.+ Cyst. (calculated)
Threonine(calculated)
Tryptophane(calculated)
Arginine(calculated)
Entire
19.7
4.8
15.8
1.98
1.57
0.2
3.28
45.8
11.81
0.48
0.75
0.19
1.76
Dehulled
20.2
2.5
15.8
1.9
1.78
0.24
2.55
66**
12.5
0.59
0.92
0.23
2.16
Beans
Hulls only Entire
19
27.4
14
10
14.2
15.1
2.21
1.55
1.3
1.46
0.2
0.16
3.91
2.85
28.5
29.6
8.97
10.09
0.4
0.49
0.62
0.87
0.16
0.2
1.46
2.3
Dehulled
29.9
5.4
14.5
1.57
1.92
0.22
2.7
33.6
11.14
0.58
1.04
0.24
2.74
Hulls only
11.9
42.1
13.6
0.83
0.4
0.03
2.2
5.9
3.4
0.12
0.22
0.05
0.57
** presumed error in starch value and estimated for ME equation
Table 2. Nutrient analysis of the various ingredients
6.2
Least cost formulations
6.2.1 The principles
The aim of least cost rationing is to meet the nutritional requirements of the animal for the
lowest possible cost, using specialist computer software. The first step is to programme in
the dietary requirements of the birds. This will vary according to species (chickens,
turkeys, ducks etc), enterprise (layer or table birds) and the stage of development (starter,
grower, finisher, layer). Table 3 gives some examples. For this reason, the value of
dehulled peas and beans will vary according to the diet it is being offered in.
The programme has a database that includes the nutritional value of a number of common
ingredients and their costs per tonne. It uses this information to arrive at the target it has
been set by the cheapest possible route
Page 5 of 13

9. Crude protein%
Lysine %
Methionine%
ME (MJ/kg)
Calcium %
Turkey -Starter
26.5
1.4
0.48
11.7
1.3
Turkey - Grower
22
1
0.4
12.2
1.05
Broiler - Finisher
22.5
1.1
0.43
12.7
0.85
Chicken - Layer
17
0.8
0.38
11.8
4
Table 3 Some poultry diet specifications
6.2.2 Calculating opportunity prices for dehulled peas and beans
It therefore follows that the inclusion or otherwise of peas and beans will depend not only
on the nutritional content but also how their cost compares with that of other ingredients
that are effectively competing for a place in the ration (We used spot prices for November
2012, quoted in Table 4). Initially the value of dehulled peas and beans were given a very
high value i.e. £7777, to ensure that they did not come into the initial formulation. The
programme then calculates the price at which rejected ingredients become competitive
and come into the formulation. This is known as the opportunity price
Ingredient
Wheat
Soya 44
Sunflower
Fish meal*
Maize
Mz Gluten 60**
Mon.Ca. phos.
Limestone
Sod.Bicarb.
Salt
Cost (£/ tonne)
318
559
330
1095
298
730
485
50
280
130
* Fish meal, as a non agricultural ingredient can be used in organic poultry diets without restriction
** The Maize Gluten 60% protein can be included up to 5% of the non mineral ingredients
Table 4 Ingredient costs
We entered values for the nutrient content of dehulled, entire and hull fractions obtained
from the analyses (Table 2) into the programme. It calculated the opportunity prices (Table
5) for each of the four rations.
Peas entire
Peas dehulled
Pea hulls
Beans entire
Beans dehulled
Bean Hulls
Turkey starter
391
440
270
343
414
Nil
Turkey grower
439
514
223
395
514
nil
Broiler finisher
274
383
Nil
101
255
nil
Chicken layer
307
359
149
221
302
Nil
Table 5: Opportunity prices of dehulled peas and beans in various rations
6.2.3 Putting a value on dehulling
Table 5 shows considerable variation between dehulled and entire pea and bean
opportunity prices, depending on the diet. We assessed the proportion (by weight) of hull
Page 6 of 13

10. to seed by directly measuring the proportion of each fraction. This was between 15 and
20% and we have calculated the benefits at the extremes of this range (Table 6 for peas,
Table 7 for beans). The analysis shows that dehulling the peas or the beans significantly
increases the value of the seed remaining. The largest increase is seen if the peas or
beans were planned for use with broilers. However the dehulled peas and beans were
most valuable if used in turkey diets which are higher in protein than broiler diets
The economic analysis would be more favourable if income could be derived from the
separated hulls. The hulls have no attraction in poultry diets because of their low ME and
the presence of anti-nutritive factors. However these are of little significance in ruminant
diets. The pea hulls look particularly attractive with 19% crude protein and the bean hulls
with nearly 12% crude protein are of value. In the costing above no income has been
attributed to bean hulls and little to pea hulls. They do therefore represent a major
opportunity to add value to the dehulling exercise. Ways of using them in ruminant feeding,
particularly direct to animals on farm is an obvious opportunity. Another opportunity is for
use as poultry litter to replace wood shavings which are becoming increasingly expensive.
Turkey
starter
Assuming 15% of the pea is hull
Value of 100 tonnes of peas
Value of 85 tonnes of dehulled
Value of 15 tonnes of hulls
Total dehulled+hulls
Difference from entire peas
Added value per tonne of pea
Assuming 20% of the pea is hull
Value of 100 tonnes of peas
Value of 80 tonnes of dehulled
Value of 20 tonnes of hulls
Total dehulled+hulls
Difference from entire peas
Added value per tonne of pea
Turkey
grower
Broiler
finisher
Chicken
layer
39100
37400
4050
41450
2350
23.5
43900
43690
3345
47035
3135
31.35
27400
32555
0
32555
5155
51.55
30700
30515
2235
32750
2050
20.5
39100
35200
5400
40600
1500
15
43900
41120
4460
45580
1680
16.8
27400
30640
0
30640
3240
32.4
30700
28720
2980
31700
1000
10
Table 6: The added value from dehulling peas
Page 7 of 13

11. Turkey
starter
Assuming 15% of the bean is hull
Value of 100 tonnes of beans
Value of 85 tonnes of dehulled
Value of 15 tonnes of hulls
Total dehulled+hulls
Difference from entire beans
Added value per tonne of bean
Assuming 20% of the bean is hull
Value of 100 tonnes of beans
Value of 80 tonnes of dehulled
Value of 20 tonnes of hulls
Total dehulled+hulls
Difference from entire beans
Added value per tonne of bean
Turkey
grower
Broiler
finisher
Chicken
layer
34300
35190
0
35190
890
8.9
39500
43690
0
43690
4190
41.9
10100
21675
0
21675
11575
115.75
22100
25670
0
25670
3570
35.7
34300
33120
0
33120
-1180
-11.8
39500
41120
0
41120
1620
16.2
10100
20400
0
20400
10300
103
22100
24160
0
24160
2060
20.6
Table 7: The added value from dehulling beans
7 Access to machinery
The relatively high cost of purchasing a dehuller, and the associated seed cleaning
equipment may act as disincentive for individual farmers to buy the necessary equipment.
However, there are options for producers to share the costs.
One possibility is for an individual to buy the machine, and to process grain for others in
the area at an agreed price per tonne. The purchaser would take responsibility for
operation and maintenance of the machine, and therefore would need be confident that
the others in the group would commit to a certain level of usage. He or she will have to
charge relatively high rates per tonne to achieve a return on his capital and to cover the
risk of not having sufficient business to pay for it. From the point of view of the other
producers there is also the risk that the single purchaser could sell the machine at any
time, if there was insufficient work, thus leaving everyone high and dry.
Another option is cooperative ownership, which is more complex, but shares the risk
among a greater number of producers. Given that everyone in the group has a stake in the
machine, and is therefore more likely to use it. The group sets up a company in which all
participants are shareholders. The company buys the equipment and then leases it to
share holders on a prorata basis, at a price that cover running costs, spares and repairs.
The machines could also be hired out to non-members on a cost per- tonne basis.
The latter option is effectively a machinery syndicate. These are highly successful on the
continent but have a somewhat chequered history in the UK. Most of the problems arose
because there was no clear agreement among members on responsibility for
maintenance, invoicing or priority of use. One solution is to involve an independent third
party, such as a machinery ring, to take on all these roles. It involves and extra cost, but
could be very important in insuring the project runs smoothly and to the benefit of all
involved.
For more information
gperkins@pmr.org.uk’
contact
Graham
Perkins,
PMR
Limited,
01437
761321
Page 8 of 13

12. 8
Conclusions
The situation with regard to protein rich organic ingredients is becoming more serious each
year. The main problem is that organic soya is becoming increasingly hard to source
because more and more GM soya is being grown.
While there are still a lot of unanswered questions, this project has demonstrated that the
dehulling of peas and beans is a promising way for the organic movement to meet the
nutritional challenges it faces. To take it further, practical ways in which the crops can be
grown, dehulled and utilised need to be devised and pilot tested. Ways of utilising the hulls
to gain maximum income are an important aspect of this work
Page 9 of 13